1. Field of the Invention
The present invention relates generally to programmable logic controllers and, more specifically, to a method of using a neutral event specification file for manufacturing line analysis for manufacturing a motor vehicle.
2. Description of the Related Art
It is known that programmable logic controller (PLC) code is written by controls engineers after assembly tooling designs are completed and a manufacturing process has been defined. The creation of the programmable logic controller code is mostly a manual programming task with any automation of the code generation limited to xe2x80x9ccutting and pastingxe2x80x9d previously written blocks of code that were applied to similar manufacturing tools. Once the programmable logic controller code is written, it is used by a programmable logic controller to build subsequent hard tools used in the manufacture of parts for motor vehicles. The programmable logic controller code is not validated (debugged) until the hard tools are built and tried. A significant portion of this tool tryout process is associated with the debugging of the programmable logic controller code at levels of detail from a tool-by-tool level, to a workcell level and finally at a manufacturing line level.
It is also known that a manufacturing line is typically made of three to twenty linked workcells. Each workcell consists of a tool such as a fixture to position a product, for example sheet metal, and associated automation, for example robots, that process the product, for example by welding. The workcell typically consists of a fixture/tool surrounded by three or four robots. The product is then transferred to the next workcell in the manufacturing line for further processing, until it exits the manufacturing line.
It is further known that the workcells for a manufacturing line can be modeled before the manufacturing line is implemented. Current modeling technologies, such as Robcad from Tecnomatix and Igrip from Delmia, for the manufacturing process are limited in scope to a workcell level, due to how these type of technologies represent and manipulate three dimensional data and tool motions. This scope limitation is due to the manner in which tooling geometry is defined and the manner in which tool motions are described and displayed to a user. The geometry representation is typically defined using Non-Uniform Rational BSpline (NURB) type equations, which are very exact and precise, but require intensive microprocessor calculations. The tooling and robotic motions are also microprocessor intensive in that the articulations and movements are described through the use of complex kinematic equations and solvers. Presently, there is no mechanism to verify that the planned interactions between linked workcells is indeed feasible until the manufacturing line is actually fabricated and assembled on a floor of a manufacturing plant.
Therefore, it is desirable to represent tooling space, tooling motions, and product information and transfer to enable integration and coordination into a manufacturing line for analysis prior to tool fabrication, assembly, and tryout. It is also desirable to provide a neutral event specification file which is not specific to any manufacturing tooling design or process planning system that contains a description of interlocked events which define the required dependencies, actions, and signals that are associated with sequencing and cycling manufacturing tooling devices. It is further desirable to provide a method that uses a neutral event specification file to enable collecting, locating, and event integration of independently defined tooling and workcell modeling for manufacturing line analysis. Therefore, there is a need in the art to provide a method of using a neutral event specification file for manufacturing line analysis for manufacturing a motor vehicle.
Accordingly, the present invention is a method of using a neutral event specification file for manufacturing line analysis. The method includes the steps of constructing a neutral event specification file having a specification format comprising at least one event, wherein each event has a name, description, at least one signal, and at least one action. The method also includes the step of executing a manufacturing line analysis model using the neutral event specification file.
One advantage of the present invention is that a method of using a neutral event specification file for a manufacturing line analysis is provided for use in building a manufacturing line to manufacture a motor vehicle. Another advantage of the present invention is that the method uses a neutral event specification file that enables integration of multiple and independently defined three dimensional CAD tooling, fixture, workcell, and product design models into a single and comprehensive total manufacturing line analysis model. Yet another advantage of the present invention is that the method enables analysis for entire manufacturing lines within one single modeling environment, prior to tooling fabrication and tryout of the actual manufacturing line. Still another advantage of the present invention is that the method provides significant reduction in programmable logic controller coding, workcell level PLC debugging, and manufacturing line level PLC debugging that is normally associated with the manufacturing line tryout procedure. A further advantage of the present invention is that the method brings together all the three dimensional product data, three dimensional tooling design data, tooling motions/behaviors, and interactions between tools and product data associated with an entire manufacturing line. Yet a further advantage of the present invention is that the method provides for pre-build verification of workcell to workcell interactions and total manufacturing line operation, so that any necessary adjustments or changes in tool design can be made while the manufacturing line is still in xe2x80x9cdesign statexe2x80x9d, rather than the current practice of not being able to test for workcell to workcell interaction issues until tool build and manufacturing line tryout.
Other features and advantages of the present invention will be readily appreciated, as the same becomes better understood, after reading the subsequent description taken in conjunction with the accompanying drawings.